This invention relates generally to gas turbine engine nozzles and more particularly, to methods and apparatus for assembling gas turbine engine nozzles.
Gas turbine engines include combustors which ignite fuel-air mixtures which are then channeled through a turbine nozzle assembly towards a turbine. At least some known turbine nozzle assemblies include a plurality of nozzles arranged circumferentially and configured as doublets. At least some known turbine nozzles include more than two circumferentially-spaced hollow airfoil vanes coupled by integrally-formed inner and outer band platforms. Specifically, the inner band forms a radially inner flowpath boundary and the outer band forms a radially outer flowpath boundary. Additionally, at least some known outer bands include a forward and an aft hook assembly that are used to couple the turbine nozzle within the engine.
Forming the turbine nozzle with a plurality of integrally-formed airfoil vanes facilitates improving durability and reducing leakage in comparison to turbine nozzles which include only one airfoil vane. However, when cooling air is channeled to the turbine nozzle, leakage may still occur between circumferentially-adjacent turbine nozzles, which are spaced apart by a gap or interface that facilitates engine assembly, and accommodates thermal expansion between the turbine nozzles. Accordingly, at least some known turbine nozzles include a seal assembly that is positioned radially outwardly from the aft hook assembly to facilitate minimizing leakage through the interface. Over time, thermal cycling may cause degradation of the seals. However, accessing such interface seals may be difficult due to the location of the nozzle.